<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <script>
    /*let str1 = "sd";
    alert(str1 + " : "+typeof str1);
    let n = 18;
    alert(n + ":" +typeof n);
    let b = true;
    alert(typeof b);*/
    let str1 = "sd";
    document.write(typeof str1+"<br/>");
    let n = 18;
    document.write(typeof n+"<br/>");
    let b = true;
    document.write(typeof b+"<br/>");
  </script>
</head>
<body>

</body>
</html>